For example, nowadays in automobiles, control of anti-lock breaking system (ABS) or traction control system (TCS) have widely been practiced, and for the control, speed of rotation of wheels must be exactly detected. Therefore, speed of rotation (number of rotation) of a rolling bearing rotatably supporting the wheels with respect to a winding device has been detected.
For detecting speed of rotation (number of rotation) of the rolling bearing, there has much served the sensor-rolling bearing with a rotating sensor installed nearly to the bearing. Namely, the sensor-rolling bearing performs detection of speed of rotation of the wheels in that a cylindrical magnet having many magnetic poles alternately arranged to a rotating side, detects a magnetic flux of the magnet rotating together with the wheels through a sensor using the hole element or the hole IC provided to a stationary side.
The sensor-rolling bearing detects speed of the movers, not limiting to the above mentioned automobiles but including those having the rotating members of such as railway carriers, and the detection of the rotating direction has been also widely practiced. The sensor-rolling bearing has been employed, in many kinds of machines of equipment, for detection of rotation speed of a motor output shaft or that of pump.
In the industrial wide field, for detecting number of rotation of the rotating members, that is, speed of rotation, or for detecting the rotating direction or phases of rotation, the sensor-rolling bearing has widely been used as the bearing of the rotating members.
The conventional sensor-rolling bearing is attached by mounting an outer ring on a bearing housing. Therefore, owing to causes such as difference in thermal expansion, a space between the outer diameter of the outer ring and the inner diameter of the bearing housing exceeds a permissible value, and the outer ring follows rotation of the inner ring and sometimes rotates along the rotating direction of the inner ring.
When the outer ring rotates in response to the rotation of the inner ring, a sensor cover mounted on the outer ring and a sensor housing also rotate concurrently. Then, an input-output signal wire taken out outside from the sensor cover and the sensor housing is effected with shearing force, because it is taken out outside via a cutout groove defined in a presser cover fixed to the bearing housing. Therefore, when the outer ring largely rotates by the rotation of the inner ring, the input-output signal wire might be broken.
Therefore, a bearing 600 with a rotating sensor (called as “rotating sensor-bearing” or “sensor-bearing” hereafter) has been proposed as shown in FIGS. 23 and 24. In the rotating sensor-bearing 600, the sensor housing 606 is provided in an outer diametrical face with whirl-stop members 606a projecting toward a radius direction passing through the sensor cover 607 receiving a rotation sensor 605 therein. The rotating sensor-bearing 600 is arranged with the whirl-stop members 606a in a cutout groove 609a of a presser cover 609, thereby preventing the outer ring 602 from rotating with the rotation of the inner ring 601 (for example, Japanese Patent Laid Open No. 2002-213472).
However, the above mentioned conventional sensor-bearing apparatus 600 is complicated in a structure of securing the whirl-stop members 606a and the sensor cover 607, so that the productivity is low.
A sensor-bearing apparatus 630 has conventionally been known as shown in FIGS. 25 and 26. FIG. 25 is a whole cross sectional view showing the sensor-bearing apparatus, and FIG. 26 is a cross sectional view along C-C line of the sensor-bearing apparatus of FIG. 25. The sensor-bearing apparatus 630 causes one end 641 of the sensor 640 to directly contact a reference face 631a of a stationary-side bearing ring 631, while it causes cut-out faces 633 of a sensor holding element 632 to fix chamfered parts 642 of the sensor 640 in order to position the sensor 640 (for example, Japanese Patent Laid Open No. 311740/1998).
The above mentioned conventional sensor-bearing apparatus 630 has been involved with a problem that a connection output portion 634 or a conductor 635 are applied with external force or vibration, so that a position of the sensor 640 is circumferentially dislocated. Then, an error in output of the sensor 640 is probably caused by the circumferential dislocation.
Therefore, the sensor-bearing apparatus 630 depends on resin insertion between the sensor holding element 632 and the reference face 631a of the stationary-side bearing ring 631 for checking the circumferential dislocation.
However, depending on the resin insertion, since a complicated process is required, there is a room for making improvement with respect to production process and cost-up, accordingly.
FIG. 27 is a cross sectional view of the element parts showing the conventional sensor-rolling bearing. This sensor-rolling bearing 700 is formed by securing a magnetically sensitive sensor 721 and a member 720 to be detected such as a magnet to the outer ring 710 or the inner ring 711.
The magnetically sensitive sensor 721 buried in a sensor carrier 723 includes a beading fixture over a full length of a concave groove 716 formed in an inner diametrical face of the outer ring via a sensor holding device 725. In addition, the member to be detected 720 is disposed on a plane part in the radius direction of an L-shaped member 722 forced in an outer diametrical face, so that the member 720 to be detected faces to the sensor 721.
In the above mentioned conventional sensor-rolling bearing 700, if a size of the bearing is small in the diametrical direction, it is difficult to secure the magnetically sensitive sensor 721 to the inner diametrical face of the outer ring 710 via the sensor carrier 723. It is also difficult to secure the member to be detected 720 to the outer diametrical face 711 of the inner ring via the L-shaped member 722.
For solving this problem, as seeing FIGS. 28 and 29, it may be assumed to provide a step portion in the outer diameter of the outer ring or the inner ring in order to fix the sensor or the member to be detected. But since a face to be processed of the step portion can not be subjected to a centerless machining, sizes are largely dispersed, and it is difficult to force and fix respective members.
In general, the sensor-rolling bearing is very often disposed nearly members generating electric noises by a motor. Therefore, by disposing locations, an external magnetic field caused by an external noise disturbs a magnetic field formed by the member to be detected, so that such probability might be caused that the sensor cannot exactly detect the magnetic field formed by the member to be detected.
Further, the sensor-bearing apparatus 800 as shown in FIG. 30 is known. FIG. 30 is a cross sectional view of the element parts of the conventional sensor-bearing apparatus. As showing in the same, the sensor-bearing apparatus 800 is structured in that the magnetic sensor 802 of the rotating sensor 801 and a pulsar ring (encoder) 803 are shielded with a sensor case fixing ring 804 of a magnetic substance and a magnetic bypath 805 so as to bypass an external leakage flux (for example, Japanese Patent Laid Open No. 2002-174258).
As another embodiment of the conventional sensor-bearing apparatus 800, there are those shown in FIGS. 31 and 32. FIG. 31 is a whole cross sectional view of the element parts showing another example of the conventional sensor-bearing apparatus 800, and FIG. 32 is an upper (seeing from an upper side of FIG. 31) and partially plan view of FIG. 31.
Referring to FIGS. 31 and 32, in the conventional sensor-bearing 850, the inner ring 852 at the right side of FIG. 31 of the rolling element 853 is secured at the outer circumferential end with a core metal 856 which is arranged with a cylindrical pulsar ring 857 of a permanent magnet. The magnetic sensor 860 is placed within the sensor case 858 leaving a space in relation with the outer circumferential face of the pulsar ring 857, while the sensor case 858 is fixed to an inside of a sensor case fixing ring 861.
In regard to the sensor-bearing 850, the magnetic bypath 862 is furnished to a further inside of the sensor case fixing ring 861 fixed to the outer ring 851 for interrupting the leakage magnetic flux flowing from a coil of the external motor into the magnetic sensor 860. Further, the sensor-bearing 850 is furnished with a side plate 863 and at the same time with a cutout window 861a at the upper part of a magnetic sensor 860 in the sensor case fixing ring 861 for interrupting the loop of the leakage magnetic flux into the magnetic sensor 860.
However, the above mentioned conventional sensor-bearing 850 is disposed with the magnetic sensor 860 such as hole elements via the pulsar ring 857 and the space in the radius direction on the outer circumference of the cylindrical pulsar ring (magnet) 857 secured as projecting to the side of the inner ring 852. Therefore, for exactly detecting magnetic change of the rotating pulsar ring 857 by means of the magnetic sensor 860, a surface part of the pulsar ring 857 opposite to the magnetic sensor 860 necessitates a length larger than decided particularly in the axial direction of the sensor-bearing 850.
Accordingly, the surface part of the pulsar ring 857 opposite to the magnetic sensor 860 cannot but project by the length larger than decided in the axial direction of the sensor-bearing 850.
As a result, the above mentioned magnetic sensor 860 has a limitation in shortening the length in the axial direction of the sensor-bearing 850, and cannot satisfy a requirement for saving a space requested for using the sensor-bearing to many kinds of devices, including speed detection of automobiles.
In addition, since the space between the pulsar ring 857 and the magnetic sensor 860 extends in the axial direction, a grease filled in a vacancy of the bearing flows along the space in the axial direction, and is ready for running outside as it is, and therefore, an improvement has been demanded for.
Further, in case the leakage magnetic flux flows owing to an external intense magnetic flux into between the inner ring 852 and the outer ring 853 of the sensor-bearing 850, the magnetic flux leaks to a side of the pulsar ring 857 or the magnetic sensor 860 via the rolling element 853. It is therefore necessary to provide another member of a shielding plate such as a magnetic bypath 862 between the sensor-bearing 850 and the magnetic sensor 860, increasing the number of parts and heightening cost, and concurrently increasing a setting-up process. Besides, an installing space is required to restrain reduction in size.
It is accordingly an object of the invention to provide the sensor-bearing apparatus and the sensor-rolling bearing, which may bring about high productivity and cost saving effect, position the sensor easily and at high precision without requiring the complicated process as the formation of resin insertion, effectively bypass the leakage magnetic flux from the outside with the less number of parts in order to avoid erroneous action of the sensor caused by electric noises of the motor, secure the requisite and enough whirl-stopping efficiency of the stationary-side bearing ring, and reduce in size by shortening the length in the axial direction.